This page includes a VB.NET sample and a C# sample that displays a DataGrid
containing two regular textbox columns and 2 columns containing databound
ComboBoxes.

To use databound comboboxes in the datagrid the sample derives a new datagrid
column style from the DataGridTextBoxColumn class
and adds overrides for the SetColumnValueAtRow,
GetColumnValueAtRow, Edit, Commit and ConcedeFocus
methods. This is performed in the DataGridComboBoxColumn class.

The Edit event is raised when the user sets the focus to the cell
containing the combobox. In this event the dimensions of the combobox are set
and an event handler is assigned to handle scrolling of the combobox.

When a value is changed in the combobox and you leave the grid cell the new
value must update the corresponding value in the bound data source. This
requires tracking when the user starts to edit the combobox value and then
commiting the changes to the data source. Hence the override to the Edit and
Commit events.

A second NoKeyUpCombo class derives a new ComboBox
whose WndProc method is overridden. This is
required to address issues when TABbing through the grid so as not to leave
focus on the combobox. It is this derived combobox that is added to the
datagrid.

While there are a number of methods that you must think about, the code is not
complicated.

The samples use fake databases and tables. But the concepts are there. You can
easily create a SQL Server or MS Access database modelled after the tables
referenced in the code. Or you can change the code to use your own real
databases. You will also need to modify the database connection string.